Ominous title! I don't play any of the "Un" sets in my cube. Mostly this is down to time saving, I don't need even more cards to consider. The main issue with the un cards is that some are too extreme or comic. You have to draw a line somewhere and that is the main thing I can't be bothered with. The only card I have ever really wanted to put in the cube is Blast from the Past but once you start down that path... Red also really doesn't need the help! Just the multiplayer and draft mechanic cards from Commander and Conspiracy are awkward enough for cube consideration, especially when it comes to rule sets for different kinds of event. So basically I have avoided Un-sets for convenience and not because I don't like them. One of the best MtG experiences I have had was a six man Unhinged draft. I think the sets are fantastic, the design and everything, all great. I see them more like an exotic, fun and different thing to do every now and again. Almost like doing a full powered cube!
Broadly speaking there are two kinds of Un card. Those which are funny in their word play and flavour but that still function like a fairly normal magic card. Then there are those that employ some whacky mechanic that isn't really a magic thing such as breath holding competitions and doing daft shit. The former are much more reasonable considerations for putting into a cube and may be used to good effect without changing the experience away from what is expected of a cube. I thought I would have a look at some of those cards from the latest Un set as it seems to be rather more powerful in the sensible card department. I won't be adding any of these into the cube.... yet. Reading some of these for the first time I am not only being more tempted to try some out than ever before but I am also considering if some of the potentials are too good and would just be tedious additions a little like True Name Nemesis.
Contraptions and augmentation seem fun but Unstable seems like the right place for them. Both are a bit unweildy both as a game mechanic and as a logistical thing! Neither are very well suited to cube based on there not being a high enough density to support them. Even if you put every single host, augmentation and contraption in the cube and had a relatively small cube you wouldn't be getting the most out of the cards. If energy can't break into the cube then these things certainly can't!
So, lets havea very quick look at some of the sensible cards that have some cube potential in the same vein as Blast from the Past.
Sword of Dungeons and Dragons
Lovely design, nice homage, but we have more than enough Swords already and this is probably the weakest. You could argue the trigger was better on this than on other things but the downgrade on protection is a big deal.
Feels like an upgrade on Etherim Sculptor. While this might not hit every artifact in your list it should hit a significant number of any non artifact spells in your deck, things like Tinker, Daretti, etc. It also has another toughness! While this isn't much of a drafting cube card, certainly not in an unpowered cube, it is potentially very dangerous in constructed and powered cubes.
When has a land that taps for 2 not been abused? This has no real cost! I can't be arsed to go and find all the cards with watermarks but I am sure there are enough to fill a deck. They don't even need to be all that great when you can power them out with cards like this. A narrow card but a potentially bomb like power level.
This is just well made. It isn't abusive or over powered but it is still pretty playable. Just a one drop with some utility and a bit of a subgame that isn't too far outside the realms of magic to be lame. The card is fairly low impact and probably a bit slow and annoying to play with in practice but the design of it is great. I would love to see a more streamlined and sensible design of this for normal magic use.
Earl of Squirrel
Well this one made me laugh! Card is poo but I adore squirrellink. It is just fun to say. I also quite like the mechanic, just not on this card. I want a 1/3 squirrellink for 1G please!
The Grand Calcutron
Wow! This is a lot of card for not much mana. This has a fancinating effect on the game upping the complexity massively both by adding in restrictions that require extreme planning to navigate and by providing much more complete information to make your choices with! While I would quite like to play with this card just to experience magic that way I fear this card will just makes games painfully slow. A number of cards in this set have that issue but this is the biggest offender by far. I want to watch my opponents face slowly work out how bad the Daze sitting as the first card in my program is for their whole program as the Calcutron hits play. I also quite want to abuse a two mana card that appears to allow me to draw five extra cards a turn... I think this card is slower than a game where both players start with Divining Tops in play and get a free trigger whenever anything happens (I guess excluding other Tops triggering or that would be a dull old draw).
I have no idea what the ratios of flavour text to not on dorks is in the cube or just in green. It doesn't really matter much. Even if it was 50/50 you could still draft and build in such a way to make this trigger from 3/4 of your dorks pretty easily. This isn't super powerful but it is cost in a way that makes it very playable. I think this would find its way into most green decks with 15 or more dorks in it. It isn't quite as fun as Sylvan Library or Search for Azcanta but it is going to get you a lot more card advantage than either. This is simple and clean enough that you could run it in a cube no trouble and it would be pretty strong. The previous cards, while potentially powerful and abused, are all a bit narrow for the cube. This really isn't. OK, I just realized tokens trigger this. I now think this is on the too good side to be something that would improve a cube.
This is likely less effective at ending a game than most of the alternative storm cards. It is still however a storm card, a known broken and abusable mechanic. It is on the cheaper side and it is blue. I can totally see this being used as a backup win mechanism with some great defensive utility if you need to blow it as part of a fizzled attempt in going off. In the right deck this should be pretty easy to wildly outclass a Lingering Souls.
Spike, Tournament Grinder
Speaking of mechanics we know to be broken... Yeah, this card is way too much. Not going near this one. Insane potential power level and abuse potential plus the need of stipulating rule sets for each format.
I would probably play this in a Tempered Steel deck.
Cool design, if a touch fiddly. Very powerful card quality but at four mana this is too pricey even if going a synergy route with Mul Daya or miracles.
Baron Von Count
Not a busted card but a playable enough one. I suspect it is pretty easy to do this in a couple of turns with a deck built around doing so. Tasigur for example does every number bar 3. As this card can be activated pretty quickly it has to be respected and dealt with. It is like a Vial Smasher the Fierce but rather more polar. Either it is a Trained Armadon or it wins the game.
Extremely Slow Zombie
Great design, probably the card I most want in the cube now despite being so vanilla. Last strike is super interesting. While it is typically a drawback it is not the largest and it does come with some perks. You can trigger a Jace, Cunning Castaway loot with it three times in one combat! This is just a very clean and easy to understand card that will lead to some nice things going on. I like how last strike encourages double blocks which in turn makes combat tricks more dangerous.
More or Less
Danger! I am not sure what the most dangerous thing this can do but it is none the less a scary card. It is too narrow for normal use, it will be draw an extra card at best and often worse. However, you can probably make a load of new infinite combos with this or just improve existing ones.
Super-Duper Death Ray
This sits somewhere between an Arc Lightning and a Searing Blaze. I like how this card gives you a nice meaty four damage removal spell that you don't lose value on when you have to aim it at small things. Having this as a burn option in hand would lead to many interesting options. You might intentionally use it on a small thing to gain maximum face damage, you may want to hold it back so you can go 1 for 1 against something with four toughness. This can punish planeswalkers quite nicely, especially the token generators. This is a well designed card. It isn't directly better than any of the decent 3 mana four damage burn options nor is it directly worse. As with last strike I would like to see this mechanic come to conventional magic in some way.
Better than One
So this card just seems utterly broken regardless of what format you play it in. If all you do is give your opponent half your deck you now have double draws for the rest of the game. You can lay two land a turn as well making this really oppressive early. In those cases it is probably correct to give stuff from hand you wont immediately need away as well to empower your new buddy. Late game you will likely be able to spare a bunch of permanents to give them that leg up. This is batty good on turn two. Literally this, the ability to cast it and six lands would be a fantastic hand. Four or five lands, this and a couple of useful cheap plays would be even better. Some cards like Wheel of Fortune get rather improved when you are playing a two verses one as well! I don't really see how this is close to fair at two mana. Luckily I won't be playing with it!
Kami of Ancient Law with a better creature type, somehow this is a pretty tempting card despite being pretty fair and dull. I just know I will want a Kami and wish it was a human and resent this card when I do.
Very Cryptic Command
Certainly not as good as the original but still a pretty dangerous card. Basic lands have one word in their name as do most of the original duals. This will hit a lot of decks pretty hard as a Mana Short. Very very few other cards have one words names in cube, most of those that do after the ones already named are instants and sorceries. If this isn't able to shut off over half their mana then this isn't a great card. The reshuffle mode is nice but somewhat of a last ditch thing. The recursion is also nice, the equivalent of the draw a card mode on the original and probably better, just a reliable safe value thing. The untap is either a limp combat trick or a way to make this effectively cost two. I can see this getting back Counterspell and untapping two lands so as to immediately cast said Counterspell. Snapcaster without the 2/1 but with the ability to hold onto your card if you need, or just Cryptic countering without the draw in that case. I think mostly you want to Mistbind Clique their land with this in their upkeep and get back something good with it. Then this is a good card with some nice extra utility. When they are all middling non-basic lands and you can't tap down anything at all this thing becomes overpriced and a little limited.
A red Umara Entangler. I can imagine wanting this to be a real card for something despite just being a bad Abbot of Keral Keep. It is a playable on theme support card and those go a good way in cube. It is the depth of support cards this set brings like this one that are the things that will make me regret not using the Un set cards most.
Over My Dead Bodies
This is a fairly solid build around card. You should be able to set up one shotting most people with this in good time to cast it, perhaps even accelerating it out too. It has some comparison to Living Death and Twilight's Call but the inbuilt haste makes it rather less effort to get lots of immediate value from it.
That is it for the sensible playable stuff so far but we are just under a third spoiled so far so I expect plenty more interesting cards to come.